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Chemically modified oximato complexes of titanium(IV) isopropoxide as new precursors for the sol–gel preparation of nano-sized titania: Crystal and molecular structure of [Ti{ONC10H16}4·2CH2Cl2]

Authors
Journal
Polyhedron
0277-5387
Publisher
Elsevier
Publication Date
Volume
30
Issue
5
Identifiers
DOI: 10.1016/j.poly.2010.12.025
Keywords
  • Oximato Complexes
  • Dihapto η2-(N
  • O) Manner
  • Hypercoordination
  • Dimeric
  • Monomeric
  • Nano-Sized
Disciplines
  • Earth Science

Abstract

Abstract Reactions of [Ti(OPri)4] with various oximes, in anhydrous refluxing benzene yielded complexes of the type [Ti{OPri}4−n{L}n], where, n=1–4 and LH=(CH3)2CNOH (1–4), C9H16CNOH (5–8) and C9H18CNOH (9–12). The compounds were characterized by elemental analyses, molecular weight measurements, FAB-mass, FT-IR and NMR (1H, 13C{1H}) spectral studies. The FAB-mass spectra of mono- (1), and di- (2), (6), (10) substituted products indicate their dimeric nature and that of tri- (3) and tetra- (4), (8) substituted derivatives suggest their monomeric nature. Crystal and molecular structure of [Ti{ONC10H16}4·2CH2Cl2] (8A) suggests that the oximato ligands bind the metal in a dihapto η2-(N, O) manner, leading to the formation of an eight coordinated species. Thermogravimetric curves of (3), (6) and (10) exhibit multi-step decomposition with the formation of TiO2 as the final product in each case, at 900°C. Low temperature (∼600°C) sol–gel transformations of (2), (3), (4), (6), (7) and (8) yielded nano-sized titania (a), (b), (c), (d), (e) and (f), respectively. Formation of anatase phase in all the titania samples was confirmed by powder XRD patterns, FT-IR and Raman spectroscopy. SEM images of (a), (b), (c), (d), (e) and (f) exhibit formation of nano-grains with agglomer like surface morphologies. Compositions of all the titania samples were investigated by EDX analyses. The absorption spectra of the two representative samples, (a) and (f) indicate an energy band gap of 3.17eV and 3.75eV, respectively.

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